The RC939 hand held 3 channel radio transmitter provides on demand ON/OFF control of a variety of switching applications (pool/spa equipment, line voltage landscape lighting, etc) from a remote location. Controls up to 3 RC613 radio receivers, up to 3 RC613L radio receivers, up to 3 RC613R radio receivers or a combination of all radio receivers. Comes with CR2D32 battery. 1 year warranty.